We are designing a device that includes some relatively strong magnets. The device is about the size of a cigaret pack and is connected to a laptop using USB. I am afraid that at the end of the day when I throw the device in my computer bag along with my laptop and my wallet that the magnet will de-magnetise my debit cards and erase my harddrive (or even flip a couple of bits).

Any useful information would be greately appreciated.

Thanks,
Einar